This invention relates to a window particularly intended for installation in an inclined or flat roof. More particularly, this invention relates to a window comprising a movable sash and a stationary frame wherein the sash is displaceable during the opening motion away from the frame substantially parallel to the plane thereof.
During the last decades, skylights or overhead windows of the tilting type have been used to an increasing extent, the said windows providing a favourable distribution of light in the room and a good insulation against heat losses as well as the possibility of an easy cleaning of the outside of the window pane, since the sash can be tilted so that its outside faces the room. On the other hand, such tilting windows may entail sealing problems for the very reason that the sash should be capable of being tilted and consequently cannot simply rest on the outside of the frame in its closed position. External cover rails are therefore required on the frame and sash elements or possibly movable sealing and locking rails between these window elements, which makes the manufacture of the window essentially more expensive and may cause trouble at the opening and closing of the window, for example on account of accumulated dirt. Another drawback of ordinary tilting windows is that in its more or less open position the sash obstructs the view and prevents the aperture surrounded by the frame from being used as an emergency exit.
These drawbacks have to some extent been eliminated in a skylight which is known from the specification of Swedish patent No. 312,500 and in which a central region of the sash is journalled in a pair of parallel arms which are in turn journalled at one side of the frame, while at the same time the opposite sash element is pivotally and displaceably connected to the frame so that it can be moved in the direction towards the said frame side during the opening of the window. In this case, the sash can in its closed position rest on the outside of the frame which results in a simplification of the sealing problem, and from this position the sash can be opened by being tilted and displaced into a position in which it is at right angles to the plane of the frame in the vicinity of the said frame side, so that a comparatively large emergency exit aperture is provided. In the case of this window, the sash will, however, in virtually any open position obstruct the view considerably, and in fact the window is first and foremost intended for being mounted in an approximately flat roof, e.g. covering a staircase.